Glossary
Cross Product (of velocity and field)
A vector operation that results in a vector perpendicular to the two input vectors, used to calculate the direction and magnitude of the magnetic force on a moving charge.
Example:
When calculating the magnetic force, the cross product of the velocity vector and the magnetic field vector ensures the resulting force is perpendicular to both.
Hall Effect
The phenomenon where a transverse voltage (Hall voltage) is generated across a conductor carrying current in a magnetic field, due to the magnetic force deflecting charge carriers to one side.
Example:
The Hall effect is utilized in magnetic field sensors found in smartphones and automotive systems to detect position or speed.
Hall Voltage
The measurable voltage created across a conductor perpendicular to both the current and the applied magnetic field, resulting from the charge separation caused by the magnetic force.
Example:
In a Hall effect experiment, a larger applied magnetic field will typically result in a proportionally larger Hall voltage across the conductor.
Lorentz Force
The total force on a charged particle in the presence of both electric and magnetic fields, calculated as the vector sum of the electric force and the magnetic force.
Example:
In a velocity selector, charged particles experience a balanced Lorentz force from perpendicular electric and magnetic fields, allowing only particles with a specific velocity to pass through undeflected.
Magnetic Field of a Moving Charge
A region of influence created around a charge when it is in motion, with its direction determined by the right-hand rule relative to the charge's velocity.
Example:
A high-speed electron beam in a cathode ray tube (CRT) monitor generates a magnetic field of a moving charge that can be detected by a nearby compass.
Magnetic Force (on a moving charge)
The force experienced by a moving charged particle when it passes through a magnetic field, always perpendicular to both the velocity of the charge and the magnetic field.
Example:
A charged particle entering a uniform magnetic field at an angle will experience a magnetic force that causes it to move in a helical or circular path.
Right-Hand Rule (for magnetic field direction)
A mnemonic used to determine the direction of the magnetic field created by a moving positive charge or current, where the thumb points in the direction of velocity/current and curled fingers show the field direction.
Example:
To find the direction of the magnetic field around a proton moving upwards, point your thumb up, and your curled fingers will show the circular right-hand rule field lines around the proton.
Right-Hand Rule (for magnetic force direction)
A mnemonic used to determine the direction of the magnetic force on a positive charge, where the index finger points to velocity, the middle finger to the magnetic field, and the thumb to the force.
Example:
If an electron moves to the right in a magnetic field pointing into the page, using the right-hand rule (and then reversing the direction for a negative charge) shows the force is upwards.